For many years, refrigerants which consist of chlorofluorocarbons (CFC), of which "FREON" is a well known commercial brand, have been the standard heat transfer media in refrigeration units, air conditioners, heat pumps, and the like. The reason for their widespread use is that CFC's are stable and non-flammatory, boil and condense in a useful temperature and pressure range, and were believed to be relatively inert and free of harmful side effects. However, it has been discovered that releasing CFC's into the atmosphere seriously impacts the ozone layer, and it is now necessary to avoid open air release of CFC's from equipment which contains them. In the normal use of refrigeration systems, the refrigerant is constantly recycled and is not released to the atmosphere. However, over time the refrigerant generally becomes contaminated in the equipment and looses its effectiveness. The common contaminants include water, air, compressor oil, hydrochloric acid, waxes, varnishes, and the like. Such contamination accelerates the rate of breakdown of the CFC, because it results in increases in compressor operating temperature. Moreover, prolonged operation at higher temperatures can cause compressor or compressor drive failure.
For many years, when a refrigeration system needed servicing, it was common practice in the industry simply to release the refrigerant to the atmosphere. That practice is no longer acceptable; nor is it responsible to abandon CFC-containing equipment because it would eventually leak out. It thus is becoming increasingly desirable to service CFC-containing units in a manner which prevents any loss to the atmosphere or the environment.
Presently, there is no easy, practical method for evacuating a charged refrigeration system of its refrigerant and storing it in a receiving container. This is primarily because of the nature of the refrigerant. Most refrigerants, (e.g., FREON) exist as a gas at room temperature and at atmospheric pressure. Within a pressurized refrigeration system at room temperature, the freon exists as both a liquid and a gas. If a direct connection were made from the refrigeration system to a receiving container, the gas would expand and the liquid would boil until enough gas would enter the receiving container to equalize the pressure in the receiving container and the refrigeration system. The net result would be that only a small amount of refrigerant would be transferred into the container.
Conventional recovery devices cool the recovered refrigerant indirectly by utilizing an evaporator coil in a sealed tank. The coolant in the evaporator coil (auxiliary refrigerant) is cooled by the standard refrigeration system. This creates a temperature difference between the auxiliary refrigerant in the coil and the refrigerant in the tank (e.g., the refrigerant to be recovered). As a result, the refrigerant in the tank is cooled, creating a pressure differential, and allowing the refrigerant from the coil to flow into the recovery tank.
Other refrigerant recovery systems utilize a pair of accumulators connected in line between a compressor and the refrigeration system to be evacuated. Still other systems involve diverting a portion of liquified gas to an evaporator coil which is in a heat exchange relationship with a condenser coil.
None of the known refrigerant reclamation systems successfully address the problem of transferring large quantities of liquid refrigerant from a large refrigeration system in an efficient and time saving manner. Typically, such known refrigerant reclamation systems remove the refrigerant from the refrigeration systems utilizing a pump which has a single mode of operation (i.e., the pumps typically do not include the ability to change their capacity or maximum pump rate). As such, the pump removes the refrigerant with the same mode of operation regardless of the phase of the refrigerant (i.e., liquid or gaseous). Typically, such pumps remove the refrigerant in its liquid phase at approximately 5 pounds per minute and remove the refrigerant in its gaseous phase at approximately 1/2 pound per minute. Thus, the prior art systems do not address the problem of removing refrigerant from the refrigeration system in both the liquid and gaseous phases.
Moreover, there exists a need for such a system which can efficiently and economically convert the phase of the refrigerant from gas to liquid. There further exists a need for a refrigerant reclamation system which is efficient and of such size as to be portable and readily utilized in the servicing of large refrigeration systems where electricity is not always available to power the system.
The present invention overcomes many of the disadvantages inherent in the conventional refrigerant reclamation systems by providing a pneumatically operated system, wherein a pneumatically operated pump has a first mode of operation for removing the refrigerant in a substantially liquid phase and a second mode of operation for removing the refrigerant in a substantial gaseous phase. Additionally, the refrigeration reclamation system of the present invention results in an efficient system for withdrawing refrigerants by utilizing the exhausted fluid from the pneumatic pump to cool the refrigerant to promote the condensation thereof. Thus, use of the present invention results in considerable savings in money as well as time for the removal of refrigeration system refrigerants.